This invention relates to a method and apparatus for an isolated, universal input, power supply, in the form of a unique single-ended resonant topology that utilizes capacitive-energy storage versus magnetic-energy storage, for converting an ac or DC input voltage to a variable voltage and current DC output or a variable ac output voltage, current, frequency, and/or phase, using a single switch and single integrated-magnetic device with inherent near-unity power factor, excellent efficiency, high power density, and very low cost.